Balloon dilatation catheter with proximal hypotube

ABSTRACT

An intravascular balloon catheter is disclosed which includes a proximal hypotube shaft segment, a distal polymer shaft segment, a distally-mounted inflatable balloon segment, and a hollow tubular member having a proximal end connected to the distal end of the hypotube shaft segment such that the lumen of the hollow tubular member is in communication with the exterior of the balloon catheter and the distal end of the hollow tubular member is connected to the distal end of the balloon.

This is a continuation of application Ser. No. 07/782,242, filed on Oct.23, 1991, pending which is a continuation of application Ser. No.07/433,711, filed on Nov. 13, 1989, now abandoned, which is acontinuation-in-part of application Ser. No. 07/162,004, filed on Feb.29, 1988, now U.S. Pat. No. 4,943,278, issued on Jul. 24, 1990.

BACKGROUND OF THE INVENTION

The present invention relates to the field of angioplasty. Inparticular, the present invention relates to a dilatation ballooncatheter.

Angioplasty has gained wide acceptance in recent years as an efficientand effective method for treating types of vascular diseases. Inparticular, angioplasty is widely used for opening stenoses in thecoronary arteries, although it is also used for treatment of stenoses inother parts of the vascular system.

The most widely used form of angioplasty makes use of a dilatationcatheter which has an inflatable balloon at its distal end. Usingfluoroscopy, the physician guides the catheter through the vascularsystem until the balloon is positioned across the stenosis. The balloonis then inflated by supplying fluid under pressure through an inflationlumen to the balloon. The inflation of the balloon causes stretching ofthe artery and pressing of the lesion into the artery wall toreestablish acceptable blood flow through the artery.

In order to treat very tight stenoses with small openings, there hasbeen a continuing effort to reduce the profile of the catheter so thatthe catheter cannot only reach but also cross such a very tightstenosis.

In addition, a percutaneous transluminal coronary angioplasty (PTCA)system has been developed by applicant's assignee which makes use of avery low profile balloon catheter or "dilating guide wire" over which asecond dilatation catheter can pass. The smaller dilating guide wire isfirst moved across a very tight stenosis, and the balloon of thedilating guide wire is inflated to partially open the stenosis.Subsequently, the larger diameter dilatation catheter is advanced overthe dilating guide wire and across the stenosis. The balloon of thelarger diameter catheter is then inflated to open further the stenosis.

The need to decrease dilatation catheter profiles has, however, broughtwith it certain practical limitations. In particular, the ability totransmit torque from the proximal to the distal end of the guide wire(or the catheter) in order to steer its distal tip through the vascularsystem and across a stenosis has been compromised. The need to reduceprofile can compromise purgeability using conventional vacuumtechniques. Therefore, there is a continuing need for improved torqueresponse and tip control along with continued efforts for reduction incatheter profile, while facilitating a positive pressure purge.

SUMMARY OF THE INVENTION

A first embodiment of the present invention is an intravascular ballooncatheter comprising a balloon having a proximal waist segment, aninflatable segment and a distal waist segment. A metallic tube isconnected to the proximal waist segment and a hollow core member isconnected at its distal end to the distal waist segment. The proximalend of the hollow core member is connected to the distal end of themetallic tube such that the lumen of the hollow core member is incommunication with the exterior of the balloon catheter. The distal endof the metallic tube may have a diminishing profile or a taper. Thedistal end of the metallic tube may also be crimped. The hollow coremember may extend through the interior of the proximal waist segment,the inflatable balloon segment, or the distal waist segment. Theproximal waist segment and the inflatable segment may be integrallyformed.

Another embodiment of the present invention is an intravascular ballooncatheter having a hypotube proximal shaft portion. A tubular member isprovided which has a proximal end connected to the distal end of thehypotube such that the lumen of the tubular member is in communicationwith the exterior of the balloon catheter. The distal end of the tubularmember is connected to the distal end of an inflatable balloon. Thedistal end of the hypotube may have a diminishing profile or taper. Thedistal end of the hypotube may also be crimped. The tubular member mayextend through the interior of the balloon.

Yet another embodiment of the present invention is an intravascularballoon catheter having an inflatable balloon, a metallic tube, andproximal waist connected therebetween. A hollow tubular member isprovided which has a proximal end connected to the distal end of themetallic tube such that the lumen of the hollow tubular member is incommunication with the exterior of the balloon catheter. The distal endof the hollow tubular member is connected to the distal end of theballoon. The distal end of the metallic tube may have a diminishingprofile or taper. The distal end of the metallic tube may also becrimped. The hollow tubular member may extend through the interior ofthe proximal waist or the inflatable balloon. The proximal waist and theballoon may be integrally formed.

A further embodiment of the present invention is an intravascularballoon catheter having an elongate shaft with a proximal portion madeof metal and a distal portion mad of a polymer. An inflatable balloon isconnected to the distal portion of the elongate shaft. A hollow tubularmember is connected to the elongate shaft such that the lumen of thehollow tubular member is in communication with the exterior of theballoon catheter. The hollow tubular member may also be connected to theinflatable balloon. The proximal metallic portion of the elongate shaftmay have a distal end which has a diminishing profile. The proximalmetallic portion of the elongate shaft may have a distal end which iscrimped. The hollow tubular member may extend at least partially throughthe interior of the balloon.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a first preferred embodiment of theballoon catheter of the present invention.

FIG. 2 is a sectional view along section 2--2 of FIG. 1.

FIG. 3 is a sectional view of a second preferred embodiment of theballoon catheter of the present invention.

FIG. 4 is a sectional view along section 4--4 of FIG. 3.

FIG. 5 is a detail view showing a brazed bond between the tube and coreshown in FIG. 4.

FIG. 6 is a sectional view of a third preferred embodiment of theballoon catheter of the present invention.

FIG. 7 is an enlarged sectional view of a distal portion of the thirdpreferred embodiment.

FIG. 8 is a sectional view along section 8--8 of FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Catheter 10 shown in FIGS. 1 and 2 is a dilatation balloon catheterwhich includes main catheter tube or shaft 12, balloon member 14, coremember 16, and spring tip 18.

Tube 12 is an elongated flexible thin walled metal tube, preferably ofstainless steel or of stainless steel with a low friction coating suchas polytetrafluoroethylene. Luer fitting 20 is mounted at the proximalend of tube 12 for connection to an inflation device (not shown) whichprovides fluid under pressure through the interior lumen of tube 12 forballoon inflation.

At its distal end, tube 12 has a section 22 of reduced outside diameterand a formed recess 24 in which the proximal end of core member 16 isattached, preferably by brazing.

Balloon member 14, which is preferably a polymer material such as apolyolefin, has a proximal or waist segment 26, a distensible balloonsegment 28, and a small diameter distal segment 30. Proximal segment 26is bonded to the distal end of tube 12 and to core member 16. Anadhesive and sealing material 32 (such as an epoxy) is provided to sealtogether tube 12 and core member 16 with the proximal segment 26 ofballoon member 14.

In the embodiment shown in FIGS. 1 and 2, core member 16 is generallyaligned parallel with tube 12 and balloon member 14 and is coaxiallyaligned except for its proximal end. Core member 16 has a proximalsection 34 of larger outer diameter and a distal section 36 of smallerouter diameter. Central vent passage 38 extends essentially the entirelength of core member 16, and opens to the exterior of catheter 10 atthe proximal end of core member 16. Vent opening 40 providescommunication between vent passage 38 and the interior of balloon member14 to allow for the positive pressure purging of air out through ventopening 40, vent passage 38, and the open proximal end of core member16.

Distal segment 30 of balloon member 14 is bonded (such as by an epoxy)to the distal end of core segment 36, such as by brazing or soldering.In FIG. 1, core segment 36 extends out slightly beyond the end of distalsegment 30, and spring tip 18 is attached to core segment 36. Spring tip18 includes a solid core segment 42 (which blocks the distal end of ventpassage 38), coiled spring 44, and brazed safety button 46. The moreproximally located portions of spring 44 are preferably bonded orotherwise attached to the outer end of distal core segment 36.

Distensible segment 28 of balloon member 14 has (by special shaping,wall thickness, or material treatment) a greater tendency to expandunder fluid pressure than waist segment 26. The inflation and deflationof balloon member 14, therefore, is primarily confined to distensiblesegment 28.

In FIG. 1, catheter 10 is shown in a condition in which distensibleballoon segment 28 is inflated. Before being inserted into the patient,catheter 10 is connected to an inflation device (not shown) and liquidis supplied under pressure through the interior of tube 12 to theinterior of balloon member 14. This liquid purges air contained withinthe interior of catheter 10 out through vent opening 40 and vent passage38 to the exterior of catheter 10. Vent opening 40 and passage 38 aresized so that fluid pressure can be supplied to inflate balloon segment28 without significant leaking of the inflation liquid, and so that airand a small plug of liquid will enter passage 38. When the air has beenpurged from the interior of catheter 10, the inflation device is thenused to draw the liquid back so as to collapse balloon segment 28 aroundcore member 16. This provides a low profile while catheter 10 is beinginserted into the patient. The plug of liquid within vent passage 38,however, blocks air from re-entering the interior of balloon segment 28.

The advance of the contrast liquid into passage 38 is controlled by twofactors. First, the liquid column is forced through the vent opening 40by pressure applied to the liquid, and liquid flow is resisted to anextent by the small diameter (about 0.001 to about 0.003 inch) of ventopening 40. Second, once the liquid has entered the passage 38,capillary action which is governed by the surface tension between theliquid and the surface characteristics and diameter of passage 38 willallow the liquid into the core along a certain length until a state ofequilibrium is reached. At this point, more pressure would be requiredto begin movement of the liquid in the column than catheter 10 can besubject to, and therefore the liquid advances no further. This appliesto both the application of positive pressure and vacuum. For thisreason, catheter 10 is not only ventable through vent opening 40 andpassage 38, but is also self-sealing. No additional seal or valve isrequired to prevent liquid and pressure from bleeding off through thisvent passage. The flow characteristics of the radiopaque liquid in thecore are dependent on optimization of the capillary action and staticbreakaway pressure shears.

Catheter 10 is then inserted into the patient and its distal end isadvanced through the patient's vascular system to the location of thestenosis which is to be treated. A significant advantage of the presentinvention is the improved "steerability", "pushability" and"torqueability" (i.e., torque transfer) characteristics which areprovided by tube 12. Unlike prior art low profile balloon catheters, inwhich the main catheter tube or shaft is made of a flexible plasticmaterial, the thin walled metal tube 12 used in catheter 10 of thepresent invention provides sufficient flexibility to traverse bends,while having improved pushability and improved torque transmittingcharacteristics.

FIGS. 3 and 4 show dilatation catheter 50, which is another embodimentof the present invention. Catheter 50 includes metal tube 52, balloonmember 54, core member 56, spring tip 58 and luer fitting 60.

Tube 52 is an elongated flexible thin walled metal tube of a materialsuch as 304 stainless steel. Tube 52 preferably has a low coefficient offriction coating, such as polytetrafluoroethylene. In one preferredembodiment of the present invention, metal tube 52 has a length of about43 inches, an inside diameter of about 0.020 inch and an outsidediameter of about 0.024 inch.

At the proximal end of metal tube 52 is luer fitting 60. An inflationdevice (not shown) is connected to fitting 60 for ballooninflation/deflation.

Balloon member 54 is mounted at the distal end of metal tube 52, and ispreferably an axially stretchable thermoplastic balloon material whichhas the ability to have small inside diameter and outside diameterdimensions and a thin wall, while still maintaining an acceptably highburst rating (for example, ten to twelve atmospheres) and a compliancecomparable to other balloons used in angioplasty dilatation catheters.Balloon member 54 has a proximal or waist segment 62, a distensibleballoon segment 64 and a distal segment 66. Balloon segment 64 is shownin FIG. 3 in its fully inflated condition.

In a preferred embodiment of the present invention, proximal waistsegment 62 has a length of about 12 inches, an outside diameter of about0.034 inch and a wall thickness of about 0.0045 inch. The proximal endof waist segment 62 overlaps and is bonded by epoxy bond 68 to thedistal end of metal tube 52 and to a portion of core member 56. Proximalend 70 of waist segment 62 is beveled to provide a smooth profile ascatheter 50 is withdrawn from the patient.

As shown in FIG. 3, the wall thickness of balloon segment 64 has a wallthickness which varies from about 0.0045 inch at the end which joinswaist segment 62, to a minimum thickness of about 0.001 to about 0.003inch in central section 64A, (depending on balloon outside diameter) toa wall thickness of about 0.004 inch at the end which joins to distalsegment 66. Central segment 64A is about 0.8 inch in length.

Distal segment 66 is bonded by an epoxy bond 72 to spring tip coil 58,which in turn is attached by braze joint 73 to core member 56. Theoutside diameter of distal segment 66 is about 0.022 inch and the insidediameter is about 0.014 inch. In the bonding region, spring tip coil 58has an outside diameter of about 0.011 inch to about 0.012 inch, and hasa similar or slightly larger outside diameter distal to the bondingregion. The diameter of the coil wire forming spring tip coil 58 isabout 0.003 inch.

Spring tip coil 58 extends about 0.8 inch beyond the distal segment 66,and is connected to the distal end of core 56 by a braze bond or safetybutton 74.

The position of the epoxy bond 72 at the same location as braze joint 73minimizes the length of the relatively stiff region formed by these twojoints.

Since the objective of catheter 50 is the ability to conform to rathertortuous passages, minimizing the lengths of the stiff region near thedistal end of catheter 50 is an advantageous feature of the presentinvention.

In the embodiment shown in FIG. 3, core member 56 includes vent tubecore 76 and solid distal core 78, which are connected together inend-to-end fashion by braze joint and marker 80.

Vent tube core 76 has four sections 76A-76D of differing outsidediameters. In a preferred embodiment, segment 76A has an outsidediameter of about 0.012 inch, segment 76B has an outside diameter ofabout 0.009 inch, segment 76C has an outside diameter of about 0.007inch, and segment 76D has an outside diameter of about 0.006 inch. Thistransition of decreasing outside diameter in the direction toward thedistal end takes advantage of typical curvature of anatomy that catheter50 will experience in the human body. Preferably, segment 76B has alength of about 4.5 inches and is flexible enough to pass through theaortic arch when the balloon segment 64 is trying to cross the lesion.Segment 76C of vent tube core 76 is preferably about 6 inches in lengthand is more flexible in order to negotiate the coronary arteries whichare typically more tortuous than the aortic arch.

Extending through vent tube core 76 is vent passageway 82, which opensto the interior of balloon segment 64 near the proximal end through ventopening 84 and opens to the exterior of catheter 50 through opening 86.Plug 87 blocks the proximal end of vent passage 82 so that pressurizedfluid from the interior of metal tube 52 cannot directly enter theproximal end passage 82 and flow out through opening 86.

As shown in FIGS. 3-5, segment 76A of vent tube core 76 is positioned inslot 88 which is formed in the distal end of metal tube 52. In apreferred embodiment, slot 88 is about 0.011 inch wide (which isslightly narrower than the outside diameter of segment 76A) and is about0.025 inch long. Slot 88 is preferably formed by electrodischargemachining, and segment 76A is brazed in position in slot 88 so that aseal is formed between segment 76A and tube 52.

This preferred bonding of vent tube core 76 to metal tube 52 has theadvantage that tube 52 and core 76 maintain good straightness withrespect to one other (which is critical for torqueability requirementsto prevent whipping of the distal end of catheter 52 as torque isapplied to tube 52). In addition, the flow lumen is not as restricted asit would be without the presence of slot 88. In addition, since both thesurfaces of vent tube core 76 and metal tube 52 are exposed duringprocessing, the weld can be more reliably made.

It should be noted that the drawings are not drawn to scale. In FIG. 3,for example, the transition of vent core tube 76 from an off-axisconnection to tube 52 to a generally coaxial position in more distalportions is much more gradual than shown.

Solid distal core 78 has a segment 78A which has the same outsidediameter (0.006 inch) as segment 76D, a segment 78B having an outsidediameter of 0.004 inch, and a flat ribbon segment 78C within spring tip58 which is about 0.001 inch thick and about 0.003 inch wide.

In a preferred embodiment of the present invention, vent tube core 76and solid distal core 78 are made of the same material, which ispreferably a high strength stainless steel or other high strength alloy.17-7 PH stainless, 18-8 PH stainless or 400 Series heat treatablestainless steel are examples of such high strength materials. The highstrength characteristics of vent tube core 76 and solid distal core 78reduces the chances of them taking on a permanent set when forcedthrough a typical tortuous human anatomy.

In another embodiment of the present invention which is generallysimilar to the embodiment shown in FIGS. 3-5, except that core member 56is a single solid core member. In this case, the vent passageway shownin FIG. 3 is not used, and core member 56 can be formed from a singlesolid wire core and then machined to the desired dimensions.

The advantage of this alternative embodiment of FIG. 5 is that generallya solid wire has somewhat greater strength and hardness than a tube ofthe same outside diameter. In addition, because core member 56 is anintegral member, a bond between two sections of the core member is notrequired. In order to purge this alternative embodiment catheter, aconventional vacuum purge can be used.

FIGS. 6, 7 and 8 show dilatation catheter 100, which is anotherembodiment of the present invention. Catheter 100 includes manifold 102,metal tube 104, core 106, waist tube 108, balloon member 110 and springtip 112.

Manifold 102 has a luer fitting 114 at its proximal end, for connectionto an inflation device (not shown) which provides fluid under pressureto catheter 100. Lure fitting 114 is connected to a first end cap 116,which in turn is connected to a manifold body 118. Manifold body 118 hasa reduced distal end portion 120, onto which is threadably mounted asecond end cap 122. Retained between second end cap 122 and distal endportion 120 are an annual compression sleeve 124 and a manifold washer126. Distal end portion 120 of manifold body 118, sleeve 124, washer 126and second end cap 122 all have central longitudinal openingstherethrough for reception of a strain relief tube 128, as seen in FIG.6. Received within strain relief tube 128, (which is preferably formedfrom a polyolefin copolymer material and adhered to tube 104) is aproximal end portion of metal tube 104, with that proximal end portionextending proximally through distal end portion 120 of manifold body 118and into an internal cavity 130 in manifold body 118. One or moreinserts 132 are also in cavity 130, to take up the space therein andreduce the need for inflation fluid in the catheter 100. First end cap116 also has a central opening therethrough, to permit inflation fluidto flow between the luer fitting 114 and cavity 130.

In a preferred embodiment, luer fitting 114 and first end cap 116 aresecured together by an adhesive material, as are first end cap 116 andmanifold body 118. In addition, second end cap 122 is preferably securedby an adhesive to distal end portion 120 of manifold body 118, inaddition to the threaded engagement thereof. Tightening of the secondend cap 122 onto distal end portion 120 of manifold body 118 compressessleeve 124 to create a seal about strain relief tube 128.

No adhesives are used to secure second end cap 122 and strain relieftube 128 to distal end portion 120 of manifold body 118 when selectiveremoval of second end cap 122 from manifold body 118 is desired. Suchremoval also relieves the gripping force on tube 104 (through strainrelief tube 128) and would permit disengagement of tube 104 and manifold102. This in turn would allow certain catheter exchange techniques whichare not possible with manifold 102 adhered to tube 104.

Tube 104 is an elongated flexible thin walled metal tube, preferably astainless hypotube with a low friction coating such aspolytetrafluoroethylene. In one preferred embodiment of the presentinvention, metal tube 104 has a length of about 44 inches, an insidediameter of about 0.017 inch, and an outside diameter of about 0.024inch (1.8 French).

At a distal end 145, tube 104 has a longitudinal slot 150 formedtherein. In a preferred embodiment, slot 150 is about 0.011 inch wide,is about 0.25 inch long.

Core 106 is an elongated member which is preferably formed from ahigh-strength stainless steel or other high-strength alloy, and which isconnected to tube 104 at a first bonding region 152. 17-7 PH stainless,18-8 PH stainless, and 300 or 400 series stainless steel are examples ofsuch high-strength materials. The high strength characteristics of core106 reduces the chances of it taking on a permanent set when forcedthrough a typically tortuous human anatomy. A proximal end 154 of core106 is received within slot 150 and brazed or soldered thereto tosecurely fasten core 106 to tube 104 to define first bonding region 152.

In the embodiment of the present invention illustrated in FIGS. 6, 7 and8, core 106 is a single solid core wire, which is reduced incross-section by elongated tapers or stepped reductions (e.g., taper155) as it extends distally from tube 104. This reduction incross-section further enhances the flexibility of core 106 as it extendsdistally, and through balloon 110.

This preferred bonding of core 106 to metal tube 104 has the advantagethat tube 104 and core 106 maintain good straightness with respect toone another (which is critical for torqueability requirements in orderto prevent whipping of the distal end of the catheter 100 as torque isapplied to tube 104). As seen in FIG. 7, proximal end 154 of core 106 isoffset from the axis of catheter 100, but assumes a central axialalignment distally of tube 104, as it extends through waist tube 108 andballoon. 110. In this regard, it should again be noted that the drawingsherein are not to scale. In FIG. 7, for example, the transition of core106 from an off-axis connection (to tube 104) to a generally coaxialposition distally therefrom is more gradual than shown.

As discussed above with reference to prior core designs, at its proximalend, core 106 may have an outside diameter of about 0.012 inch, reducingin size distally (for increased distal flexibility) until it is receivedwithin spring tip 112. In its very distal portions, core 106 may beformed as a thin, flat ribbon segment within spring tip 112, which isthen secured to spring tip 112 at the distal end thereof by a weldedsafety button 156. Preferably, one or more radiopaque markers 157 aresecured to core 106 and spring tip 112 is formed from radiopaquematerial (such as a platinum alloy) to aid in locating catheter 100 inthe patient's vascular system by fluoroscopy.

Waist tube 108 is an elongated flexible tube, also mounted to tube 104as seen in FIG. 7, and is preferably formed from a polymer material sucha high density polyethylene (which is a relatively lubricious, flexibleand high strength material). A proximal end 158 of waist tube 108extends proximally over distal end 145 of tube 104. Proximal end 158 ofwaist tube 108 is secured concentrically about tube 104 by a suitableadhesive 159 (such as cyanoacrylate), at a second bonding region 160proximally spaced from first bonding region 152 between tube 104 andcore 106. Those distal portions of tube 104 in bondings regions 152 and160 are not coated with lubricious material.

Waist tube 108 extends distally about core 106 from tube 104. At itsproximal end 158, waist tube 108 has an outer diameter of about 0.031inch, and tapers down to an outer diameter of about 0.026 inch distallytherefrom. In this reduced distal section, the inner diameter of waisttube 108 is about 0.021 inch, and this reduced section is about 11.10inches long. Preferably, the wall thickness of waist tube 108 is about0.0025 inch. The reduction in diameters of waist tube 108 (andaccordingly, catheter 100) allows better flexibility and "trackability"for catheter 100 in the patient's vascular system. By injectingradiopaque dyes therein, the patient's arterial lumens are made visibleon a fluoroscope. Reducing the diameter of catheter 100 allows more dyeto flow adjacent and around catheter 100, thus making the lumen areasmore visible which further aids in the positioning of catheter 100 inthe artery and evaluation of dilatation performance.

By mounting proximal end 158 of waist tube 108 to tube 104 proximally offirst bonding region 152 between tube 104 and core 106, a smootherexternal surface transition is presented and made between components ofcatheter 100 adjacent distal end 145 of tube 104. Further, there are nomaterial discontinuities or bumps adjacent first bonding region 152external of catheter 100. This arrangement also provides a more uniformbond structure (annular with no obstructions) for securing waist tube108 to tube 104 than might otherwise be possible (see, e.g., FIG. 8).

At its distal end 161, waist tube 108 is connected to a proximal balloonsegment or waist 162 of balloon 110, using a suitable adhesive andsealing material 163 (such as an epoxy) thereby defining a third bondingregion 163A. As in the prior described embodiments, balloon 110 ispreferably formed from an axially-stretchable thermoplastic balloonmaterial which has the ability to have small inside diameter and outsidediameter dimensions, and a thin wall, while still maintaining anacceptably high burst rating (for example, 10 to 12 atmospheres) and acompliance comparable to other balloons used in angioplasty dilatationcatheters. Preferably, this balloon material is formed from a polymermaterial such as polyolefin copolymer.

Balloon 110 has a distensible balloon segment 164 (shown in FIG. 7 inits fully inflated condition) and a distal balloon segment or waist 166.In a preferred embodiment of the present invention, proximal waist 162has a length of about 0.50 inch, an outer diameter of about 0.031 inchand a wall thickness of about 0.005 inch. The wall thickness ofdistensible balloon segment 164 varies from about 0.005 inch at the endwhich joins waist 162, to a minimum thickness of about 0.0018 inch toabout 0.0025 inch in central section 164A (depending upon balloonoutside diameter) to a wall thickness of about 0.005 inch at the endwhich joins to distal waist 166. Central segment 64A is about 0.80 inchin length. Distal waist 166 of balloon 110 is bonded by an adhesive bond168 (such as cyanoacrylate) to spring tip 112 (thereby defining a fourthbonding region 168A), which is in turn attached by weld joint 156 tocore 106. The outer diameter of distal waist 166 is about 0.021 inch to0.029 inch (depending upon balloon outside diameter) and the innerdiameter is about 0.016 inch. In fourth bonding region 168A, spring tip112 has an outer diameter of about 0.014 inch. The diameter of the coilwire which is helically wound to form spring tip 112 is about 0.003inch.

Spring tip 112 extends about 0.89 inch beyond distal waist 166 ofballoon 110. Although not shown in FIG. 7, spring tip 112 is alsoconnected to core 106 proximally of joint 156 by a brazed or solderedbond within fourth bonding region 168A, as illustrated for the similarcatheter spring tip structure seen in FIG. 3.

In a preferred embodiment of catheter 100, a vent tube 175 is disposedwithin balloon 110. Vent tube 175 has a proximal end 177 and a distalend 179. At its distal end 179, vent tube 175 is flattened and securedwithin epoxy bond material 168 of fourth bonding region 168A. Vent tube175 extends proximally therefrom through the interior of balloon 110 andhas its proximal end 177 secured within epoxy bond 163 of third bondingregion 163A between waist tube 108 and proximal waist 162 of balloon110. At its proximal end 177, vent tube 175 has an outlet 181 which isopen to the exterior of catheter 100. Adjacent its distal end 179 andwithin the interior of balloon 110, vent tube 175 has one or more inlets183 to facilitate the passage of gases from the interior of balloon 110into vent tube 175 and to outlet 181. In a preferred embodiment, venttube 175 has an outer diameter of about 0.003 inch and an inner diameter(vent lumen) of about 0.002 inch, and is made of material such aspolyimide.

Prior to use in a patient, catheter 100 is connected to an inflationdevice (not shown) through luer fitting 114 and inflation fluid(typically, a 50/50 solution of radiopaque dye and saline) is suppliedunder pressure through the interior of tube 104 and waist tube 108 tothe interior of balloon member 110. This fluid pressurizes balloon 110and purges air contained within the interior of catheter 100 out throughinlet 183 of vent tube 175 and through tube 175 to the catheter'sexterior via outlet 181. Vent tube 175 and its openings are sized suchthat fluid pressure can be supplied to inflate balloon 110 withoutsignificant leaking of inflation fluid, and so that air and a small plugof fluid will enter vent tube 175. When the air has been purged from theinterior of catheter 100, the inflation device is then used to draw thefluid back so as to depressurize catheter 100 and collapse balloon 110around core 106 (waist tube 108 does not collapse, however, because itis formed from a high strength material). This provides a low profilefor balloon 110 while catheter 100 is being inserted into the patient'svascular system. The plug of liquid within vent tube 175, however,blocks air from re-entering the interior of balloon 110.

The advance of inflation fluid into vent tube 175 is controlled by thesame factors as discussed above with respect to the advance of contrastliquid into passage 38 in the embodiment illustrated in FIGS. 1 and 2.Again, this applies both during the application of positive pressure andvacuum. Accordingly, catheter 100 is not only ventable through vent 175,but also self-sealing in that no additional seal or valve is required toprevent inflation fluid and pressure from bleeding off vent tube 175.

After purging, catheter 100 is used by inserting it into the patient'svascular system until its distal end is advanced to the location of thestenosis to be treated. The use of a thin-walled metal tube results insignificant advantages in steerability, pushability and torqueabilitycharacteristics for catheter 100. Thin-walled metal tube 104 providessufficient flexibility through traverse bends in the vascular system,yet has pushability and torque transmitting characteristics not found inprior art fixed wire catheters. In addition, the use of a hypotube forthe relatively long proximal section of the catheter tube provides atube with a smaller outer diameter, thereby providing enhancedtrackability during the angioplasty procedure.

In conclusion, the present invention is an improved angioplastydilatation balloon catheter of the "non-over-the-wire" type. In otherwords, it does not require a guide wire which passes through its entirelength. With the present invention, a very low shaft diameter can beachieved without sacrificing pushability or torque transfercharacteristics.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

What is claimed is:
 1. An intravascular balloon catheter, comprising:a.a balloon having a proximal waist segment, an inflatable segment and adistal waist segment; b. a metallic tube having a proximal end, a distalend and an inflation lumen extending therethrough, the distal end of themetallic tube connected to the proximal waist segment of the balloon,the distal end of the metallic tube having a crimped portion; and c. ahollow core member having a proximal end, a distal end and a lumentherein, the proximal end of the hollow core member connected to thedistal end of the metallic tube such that the lumen of the hollow coremember is in communication with the exterior of the balloon catheter,the distal end of the hollow core member connected to the distal balloonwaist.
 2. An intravascular balloon catheter, comprising:a. a balloonhaving a proximal waist segment, an inflatable segment and a distalwaist segment; b. a metallic tube having a proximal end, a distal endand an inflation lumen extending therethrough, the distal end of themetallic tube connected to the proximal waist segment of the balloon;and c. a hollow core member having a proximal end, a distal end and alumen therein, the proximal end of the hollow core member connected tothe proximal waist segment such that the lumen of the hollow core memberis in communication with the exterior of the balloon catheter, thedistal end of the hollow core member connected to the distal balloonwaist, the proximal end of the hollow core member partially laterallyoffset form the distal end of the metallic tube.
 3. An intravascularballoon catheter as in claim 1 or 2, wherein the distal end of themetallic tube has a diminishing profile.
 4. An intravascular ballooncatheter as in claim 1 or 2, wherein the inflatable segment of theballoon has an interior and the hollow core member extends at leastpartially through the interior of the inflatable segment.
 5. Anintravascular balloon catheter as in claim 4, wherein the distal end ofthe metallic tube has a diminishing profile.
 6. An intravascular ballooncatheter as in claim 1, 2 or 5 wherein the distal waist segment of theballoon has an interior and the hollow core member extends at leastpartially through the interior of the distal waist segment.
 7. Anintravascular balloon catheter, comprising:a. a balloon having aproximal waist segment, an inflatable segment and a distal waistsegment; b. a metallic tube having a proximal end, a distal end and aninflation lumen extending therethrough, the distal end of the metallictube connected to the proximal waist segment of the balloon, the distalend of the metallic tube having a lateral portion removed and a distallyfacing opening in fluid communication with the inflation lumen; and c. ahollow core member having a proximal end and a lumen therein, theproximal end of the hollow core member connected to the proximal waistsegment such that the lumen of the hollow core member is incommunication with the exterior of the balloon catheter.
 8. Anintravascular balloon catheter as in claim 1 or 2, wherein the proximalwaist segment of the balloon has an interior and the hollow core memberextends at least partially through the interior of the proximal waistsegment.
 9. An intravascular balloon catheter as in claim 1, 2 or 7wherein the proximal waist segment of the balloon and the inflatablesegment of the balloon are integrally formed.
 10. An intravascularballoon catheter, comprising:a. a hypotube proximal shaft portion havinga proximal end and a distal end, the distal end of the hypotube shafthaving a crimped portion; b. a tubular member having a proximal end, adistal end and a lumen extending therethrough, the proximal end of thetubular member connected to the distal end of the hypotube shaft suchthat the lumen of the tubular member is in communication with theexterior of the balloon catheter; and c. a balloon having a distal end,the distal end of the balloon connected to the distal end of the tubularmember.
 11. An intravascular balloon catheter, comprising:a. a hypotubeproximal shaft portion having a proximal end and a distal end; b. aballoon having a proximal end and a distal end; and c. a tubular memberhaving a proximal end, a distal end and a lumen extending therethrough,the proximal end of the tubular member connected to the proximal end ofthe balloon such that the lumen of the tubular member is incommunication with the exterior of the balloon catheter, the distal endof the tubular member connected to the distal end of the balloon, theproximal end of the tubular member connected to and partially laterallyoffset form the distal end of the hypotube shaft.
 12. An intravascularballoon catheter as in claim 10 or 11, wherein the distal end of thehypotube shaft has a diminishing profile.
 13. An intravascular ballooncatheter as in claim 10 or 11, wherein the balloon has an interior andthe tubular member extends at least partially through the interior. 14.An intravascular balloon catheter as in claim 13, wherein the distal endof the metallic tube has a diminishing profile.
 15. An intravascularballoon catheter, comprising:a. an inflatable balloon segment; b. ametallic tube having a proximal end, a distal end and an inflation lumenextending therethrough, the distal end of the metallic tube having acrimped portion; c. a proximal waist having a proximal end, a distal endand a lumen extending therethrough, the proximal end of the proximalwaist connected to the distal end of the metallic tube, the distal endof the proximal waist connected to the inflatable balloon segment; d. adistal waist having a proximal end and a distal end, the proximal end ofthe distal waist connected to the inflatable balloon segment; and e. ahollow tubular member having a proximal end, a distal end and a lumentherein, the proximal end of the hollow tubular member connected to thedistal end of the metallic tube such that the lumen of the hollowtubular member is in communication with the exterior of the ballooncatheter, the distal end of the hollow tubular member connected to thedistal waist.
 16. An intravascular balloon catheter, comprising:a. aninflatable balloon segment; b. a metallic tube having a proximal end, adistal end and an inflation lumen extending therethrough; c. a proximalwaist having a proximal end, a distal end and a lumen extendingtherethrough, the proximal end of the proximal waist connected to thedistal end of the metallic tube, the distal end of the proximal waistconnected to the inflatable balloon segment; d. a distal waist having aproximal end and a distal end, the proximal end of the distal waistconnected to the inflatable balloon segment; and e. a hollow tubularmember having a proximal end, a distal end and a lumen therein, theproximal end of the hollow tubular member connected to the proximalwaist such that the lumen of the hollow tubular member is incommunication with the exterior of the balloon catheter, the distal endof the hollow tubular member connected to the distal waist, the proximalend of the hollow tubular member partially laterally offset form thedistal end of the metallic tube.
 17. An intravascular balloon catheteras in claim 15 or 16, wherein the distal end of the metallic tube has adiminishing profile.
 18. An intravascular balloon catheter as in claim15 or 16, wherein the inflatable balloon segment has an interior and thehollow tubular member extends at least partially through the interior ofthe inflatable segment.
 19. An intravascular balloon catheter as inclaim 18, wherein the distal end of the metallic tube has a diminishingprofile.
 20. An intravascular balloon catheter, comprising:a. aninflatable balloon segment; b. a metallic tube having a proximal end, adistal end and an inflation tureen extending therethrough, the distalend of the metallic tube having a lateral portion removed and a distallyfacing opening in fluid communication with the inflation lumen; c. aproximal waist having a proximal end, a distal end and a lumen extendingtherethrough, the proximal end of the proximal waist connected to thedistal end of the metallic tube, the distal end of the proximal waistconnected to the inflatable balloon segment; d. a distal waist having aproximal end and a distal end, the proximal end of the distal waistconnected to the inflatable balloon segment; and e. a hollow tubularmember having a proximal end and a lumen therein, the proximal end ofthe hollow tubular member connected to the proximal waist such that thelumen of the hollow tubular member is in communication with the exteriorof the balloon catheter.
 21. An intravascular balloon catheter as inclaim 15, 16 or 20 wherein the proximal waist has an interior and thehollow tubular member extends at least partially through the interior ofthe proximal waist.
 22. An intravascular balloon catheter as in claim15, 16 or 20 wherein the proximal waist and the inflatable balloonsegment are integrally formed.
 23. An intravascular balloon catheter,comprising:a. an elongate shaft having a proximal portion and a distalportion, the proximal portion made of a metallic material and the distalportion made of a polymer material, the metallic portion having acrimped distal end; b. an inflatable balloon connected to the distalportion of the elongate shaft; and c. a hollow tubular member having aproximal end, a distal end and a lumen therein, the proximal end of thehollow tubular member connected to the elongate shaft such that thelumen of the hollow tubular member is in communication with the exteriorof the balloon catheter.
 24. An intravascular balloon catheter,comprising:a. an elongate shaft having a proximal portion and a distalportion, the proximal portion made of a metallic material and the distalportion made of a polymer material; b. an inflatable balloon connectedto the distal portion of the elongate shaft; and c. a hollow tubularmember having a proximal end, a distal end and a lumen therein, theproximal end of the hollow tubular member connected to the elongateshaft such that the lumen of the hollow tubular member is incommunication with the exterior of the balloon catheter, the proximalend of the hollow tubular member partially laterally offset form thedistal end of the metallic portion of the shaft.
 25. An intravascularballoon catheter as in claim 23 or 24, wherein the distal end of thehollow tubular member is connected to the inflatable balloon.
 26. Anintravascular balloon catheter as in claim 23 or 24, wherein theproximal metallic portion of the elongate shaft has a distal end whichhas a diminishing profile.
 27. An intravascular balloon catheter as inclaim 23 or 24, wherein the inflatable balloon has an interior and thehollow tubular member extends at least partially through the interior.28. An intravascular balloon catheter as in claim 27, wherein theproximal metallic portion of the elongate shaft has a distal end whichhas a diminishing profile.
 29. An intravascular balloon catheter,comprising:a. a balloon having a proximal end and a distal end; b. ahypotube proximal shaft portion having a proximal end and a distal end,the distal end of the hypotube shaft having a lateral portion removedand a distally facing opening in fluid communication with the inflationlumen; and c. a tubular member having a proximal end and a lumenextending therethrough, the proximal end of the tubular member connectedto the proximal end of the balloon such that the lumen of the tubularmember is in communication with the exterior of the balloon catheter.30. An intravascular balloon catheter, comprising:a. an inflatableballoon; b. an elongate shaft having a proximal portion and a distalportion, the proximal portion made of a metallic material and the distalportion made of a polymer material, the balloon connected to the distalportion, the distal end of the metallic portion of the shaft having alateral portion removed and a distally facing opening in fluidcommunication with the inflation lumen; and c. a hollow tubular memberhaving a proximal end, a distal end and a lumen therein, the proximalend of the hollow tubular member connected to the elongate shaft suchthat the lumen of the hollow tubular member is in communication with theexterior of the balloon catheter.